1. Field of the Invention
The present invention is directed to a rotating trommel for screening or filtering material of different sizes. In particular, the present invention is directed to a rotating trommel wherein the openings or orifices are variable in size.
2. Prior Art
The use of trommels to screen or filter particulate material to separate material under a chosen size is well known. One type of trommel is a substantially cylindrical trommel having openings or orifices in the walls. The trommel is rotated about its cylindrical axis so that the force of gravity causes the material to tumble within the trommel. Particles smaller than the size of the openings will fall through the openings and be separated out.
One application for such trommels is in metal recycling systems. The recovery of valuable metals from waste effluents is increasingly important since there are only two options for managing such wastes disposal or recycling.
Recovery of valuable metals by recycling waste automobiles is one metal recycling usage. Waste automobiles are initially shredded and the particulate material is separated for recycling. The automobiles are initially shredded and then processed to separate ferrous (magnetic) material from nonferrous (nonmagnetic) material by use of a magnetic separation unit.
The nonferrous residue is known to contain a small percentage of nonferrous metallics. The percentage of nonferrous metallics in the nonferrous stream ranges from 30 percent up to 65 percent. The nonferrous metallics include aluminum, zinc, copper, brass and stainless steel.
The non-metal remaining material typically includes plastic, fluff, coated electrical wire, rubber, rock and glass particles.
To increase the quality of the nonferrous metallics in the residue, the residue is often passed through a rotating screen trommel.
The trommel itself is rotated about its axis so that the materials will move upward in response to the trommel and they will fall back down by force of gravity. Ideally, the nonferrous material will tumble a number of times as it passes through the tube. Presently, internally extending strike plates are utilized as an example, the trommel may be provided with openings to allow material less than 1/2 inch in size to fall through. Depending on the waste material being processed, it may be desirable to vary the size of the orifices in the trommel.
There is a need to provide a trommel wherein the particulate matter will be tumbled by rotation of the trommel and force of gravity.
There is additionally a need to provide a trommel wherein the size of the orifices and, therefore, the size of the materials separated, is variable.